1. Technical Field
The present invention relates to pipe hangers for use underneath slab foundations of concrete and reinforced steel construction. Even more particularly, the present invention relates to a hanger for supporting pipes underneath concrete slab foundations wherein the hanger is supported by and preliminarily connected to the slab foundation reinforcing steel before concrete is poured.
2. General Background
In the construction of homes, office buildings and other such structures, it is common to use a foundation of reinforced concrete prior to construction of the building superstructure. Most conventional homes, for example, use a four-inch concrete slab which is reinforced with steel reinforcing bars, wire mesh or the like. The use of concrete and reinforcing steel is well-known in the art and documented by building codes of numerous types such as, for example, ALSC and ASTM codes and local and state building codes.
In order to construct a concrete slab foundation, a form is first placed upon the earth at the exact position where the slab will be cast. The form is usually constructed of wood which is temporarily supported in a desired position by a carpenter. The wood defines the horizontal dimensions of the slab as well as the top surface elevation of the slab, usually in a horizontal plane. The lowermost surface of the slab is defined by the underlying earth. Pipes can be mounted under the slab in the underlying earth prior to pouring of the concrete into the foundation form. Reinforcing steel for preventing failure of the slab because of tension can be placed in the space defined by the form prior to a pour. The placement and size of reinforcing steel is normally governed by a building code, or by known engineering standards. The reinforcing steel is usually positioned vertically between the upper and lower limits of the slab such as, for example, two inches below the surface of a four-inch slab.
In some areas, a problem exists where slabs settle or drop in elevation over a period of time. This is a problem in low lying areas, or in areas which have poor soil conditions such as, for example, vegetable matter contained within the underlying soil mass. Other areas simply have a continuous day-to-day, year-to-year drop in the overall soil elevation due to a number of long term geological factors. For example, in swampy and marshy areas, entire cities are slowly dropping in elevation because of the problem of geological soil subsidence. In these cities, buildings must use piling to maintain a proper elevation of the building slab. Piling are used to maintain the slab in a given horizontal position. A problem exists with regard to appurtenances to the structure such as piping, for example. Many homes are supplied with pipes for sewage and drainage. These pipes can settle, crack and produce disasterous consequences such as explosion, fire, loss of property and loss of life. In order to prevent settling of pipes under slab foundations, it is desirable to affix the pipe horizontally with respect to the slab foundation so that the pipeline does not drop in elevation with respect to the slab causing the aforementioned disasterous consequences.
Various devices have been patented as pipe hangers for the affixation of pipes to concrete and concrete-like structures. Note, for example, U.S. Pat. No. 1,362,245 entitled "Hanger Pipe," issued to J. W. Farley on Dec. 14, 1920. In this device there can be seen a pipe hanger which uses a suspensory member made in one piece bent into stirrup form to provide a short leg and a long leg, and a supplemental piece which is fixed to the first member and adapted to anchor the same within a concrete floor.
In U.S. Pat. No. 1,804,420 there is provided a "Ceiling Supporting Strap." In that patent the strap comprises a supported strap, an anchoring strap, means for suspending the supported strap at one side from the lower end of the anchoring strap and a lip formed to extend outwardly from the side of the anchoring strap, the lip being adapted to be bent into a position across the upper end of the supported strap to prevent displacement therefrom.
A pipe hanger is the subject of U.S. Pat. No. 1,769,015. That patent relates to connecting links or hangers which support pipes and other things that are connected or suspended from an overhead support. The hanger uses a bar of metal having provision at one end for attachment to the ceiling and the other end provides a bentback portion forming an eye for engaging the pipe. The bentback portion is locked to the body portion of the eye by a link or band which directly embraces the two. The link maybe an ordinary washer.
U.S. Pat. No. 3,620,490 entitled "Cable Hanger" discloses a cable hanger adapted to fit into a blind hole of a mine roof so as to suspend cable or other power conduit from the roof of a mine. The cable hanger comprises a shaft, bent at one end to form a hook and threaded at the other end for the provision of an expansion shell. The expansion shell consists of an upper relatively immovable member having a smooth axial bore for fitting over the threaded portion of the shaft and a movable lower member containing a smooth axial bore for a slidable fit over the threaded portion of the shaft. Each member has an angularly beveled engaging end surface designed to slide diagonally upwardly and downwardly and laterally or medially over the complementary angularly beveled end surface of the other.
A British Pat. No. 1,392,237 provides a support member including a length of strap metal which is formed into a loop to encircle a set of pipes.
Austrian Patentschrift No. 26409 issued Nov. 10, 1906 shows a hanger having a loop formed in one end portion thereof.